U.S. Pat. No. 4,298,025, which is owned by the present assignee, discloses a control valve for use in water softeners having two resin tanks. One of the resin tanks is normally on-line while the other tank is regenerated and placed in a standby condition until the first tank requires regeneration. The disclosed control valve controls which of the tanks is on-line and controls the regeneration sequence of an exhausted tank.
The quantity of water treated by a given tank, is monitored by a mechanism that includes a water usage turbine driven by water entering the on-line resin tank. When a predetermined quantity of water is treated, which produces to a predetermined number of revolutions in the turbine, a regeneration sequence is initiated which places the standby tank on-line and isolates the exhausted tank.
A second turbine, operatively connected to a regeneration sequence control element (in the form of a disk) is rotated by a stream of water that is activated at the beginning of the regeneration cycle. The stream of water physically drives the regeneration control disk (via the turbine and associated drive train) through its sequence. With the disclosed arrangement, the frequency of regeneration of the water softener system is determined by the usage turbine which directly measures the quantity of fluid treated by a given tank.
In Pat. No. 4,427,549 which is also owned by the present assignee, a deionization method and apparatus is disclosed. The disclosed apparatus includes a control valve similar to the control valve disclosed in U.S. Pat. No. 4,298,025 in that it includes a usage turbine for monitoring the amount of source water treated by a given tank and a regeneration control turbine for driving a control element through a regeneration sequence.
In the control valves disclosed in the above-identified patents, the last step in the regeneration sequence is a water rinse that is performed in the counterflow direction. It is known that a fast rinse in the service direction or "downflow" rinse provides certain advantages over a rinse in the counterflow direction. For example, a downflow fast rinse tends to pack the media bed making the operation of the bed more effective upon initial start-up. Attempts have been made to provide a downflow fast rinse in the type of control valve disclosed in the above-identified patents, but these attempts have resulted in undue complexity in the valve, and the need for creating additional fluid signals in order to provide the necessary rinse function.
It has also been found desirable to improve the overall efficiency of the type of valve disclosed in the above-identified patents, so that the amount of water consumed during regeneration is reduced.